Take-up spool latch

Claim 2

In a seat belt retractor having a spool frame, a spool journalled for rotation in the spool frame, and a torsion imparting spring operably connected between the spool and the spool frame arranged for retracting a belt when carried on the spool, a take-up spool latch comprising: a clutch member coaxial with the spool and in frictional engagement with the spool, a brake member coaxial and rotatable with respect to the spool and in frictional engagement with the spool frame, interengaging means between the clutch and brake members limiting relative rotation therebetween, cam surfaces on both the clutch member and the brake member, a ratchet having ratchet teeth on the spool, and a pawl pivoted to the spool frame for engaging the cam surfaces of both the clutch and brake members and the ratchet teeth, the cam surfaces controlling the engagement of the pawl with the ratchet teeth such that: a. upon retraction of a seat belt which has been withdrawn from the spool, the cam surfaces pivot the pawl out of engagement with the ratchet teeth, b. upon initial further withdrawal and during said limited relative rotation between the clutch and brake members, the pawl is released by the cam surfaces and pivots to engage the ratchet teeth thereby preventing retraction, and c. upon further withdrawal to and beyond said limited relative rotation accomplished by the interengaging means, the cam surfaces again engage the pawl and pivot it out of engagement with the ratchet teeth.

Claim 3

A take up spool according to claim 1 wherein the clutch member and brake member are both discoid members, said cam surfaces being peripheral surfaces of said respective said discoid members.

Claim 4

A take up spool according to claim 2 wherein the spool includes an end plate and each said discoid member is provided with an annular friction pad, the friction pad of said clutch member bearing against said end plate of the spool, the friction pad of said brake member bearing against the spool frame, the effective mean radius of the friction pad of the clutch member being greater than the effective mean radius of the friction pad of the brake member, and a spring between the clutch and brake members effecting said frictional engagements.

Claim 5

A take up spool according to claim 2 wherein said interengaging means between the clutch and brake members includes a spigot outstanding from a face of one said members movable in a circumferential recess in the periphery of the other said member.

Claim 6

A take up spool according to claim 2 wherein said pawl is a double lobe pawl, one lobe extending over the peripheries of both said discoid members, the other lobe being that portion of said pawl which is releasably engagable in the said ratchet teeth.

Claim 7

A take up spool according to claim 2 further comprising a brake lug projecting from a face of the brake disc, and an arcuate slot in the spool frame, the brake lug being movable in the arcuate slot but said movement bEing limited by the ends of said slot.

Claim 8

In a seat belt retractor having a spool frame, a spool journalled for rotation in the spool frame, and a torsion imparting spring operably connected between the spool and the spool frame arranged for retracting a belt when carried on the spool, a take up spool latch comprising: a clutch disc and a brake disc both coaxial and rotatable with respect to the spool, a spring between said discs urging the clutch disc into frictional engagement with the spool and the brake disc into frictional engagement with the spool frame, interengaging means between the brake disc and the spool frame limiting rotary movement of the brake disc, a radially inwardly extending pawl recess in the periphery of the brake disc, a radially inwardly extending recess in the periphery of the clutch disc of greater circumferential length than the pawl recess, said peripheries and recesses forming co-operating cam surfaces, a spigot outstanding from a face of one of the discs, and co-operable limit means on the other disc engageable by the spigot to thereby limit relative rotation of discs to a degree exceeding said limited rotary movement of the brake disc, a ratchet having ratchet teeth on the spool, a pawl pivoted on the spool frame arranged to engage the ratchet teeth and also to engage the cam surfaces, the inter-relation of said interengaging means, cam-forming recesses and limit means being so arranged that: a. upon retraction of a seat belt which has been withdrawn from the spool, the clutch disc is urged to rotate owing to said frictional engagement with the spool and the brake disc is urged by the spigot to rotate, whereby the pawl recess moves into alignment with the pawl but the cam surface of the clutch disc pivots the pawl out of engagement with the ratchet teeth, b. upon initial further withdrawal of the seat belt from the spool and during said limited relative rotation between said clutch and brake discs the clutch disc is urged to rotate in a reverse direction to place its radially inwardly extending recess into alignment with the pawl, whereby the pawl pivots to engage the teeth of the ratchet, and, c. upon further withdrawal beyond the limit of said limited relative rotation of the discs, the spigot of the clutch disc imparts rotation to the brake disc and the cam surface of the brake disc lifts and pivots the pawl out of engagement with the ratchet teeth.

Claim 9

In a seat belt retractor having a spool frame, a spool journalled for rotation in the spool frame, and a torsion imparting spring operably connected between the spool and the spool frame arranged for retracting a belt when carried on the spool, a take up spool latch comprising: a clutch disc and a brake disc both coaxial and rotatable with respect to the spool, a spring between said discs urging the clutch disc into frictional engagement with the spool and the brake disc into frictional engagement with the spool frame, interengaging means between the brake disc and the spool frame limiting rotary movement of the brake disc, a radially inwardly extending pawl recess in the periphery of the brake disc, a radially inwardly extending recess in the periphery of the clutch disc of greater circumferential length than the pawl recess, said peripheries and recesses forming co-operating cam surfaces, a spigot outstanding from a face of one of the discs, and co-operable limit means on the other disc engageable by the spigot to thereby limit relative rotation of discs to a degree exceeding said limited rotary movement of the brake disc, a ratchet having ratchet teeth on the spool, a pawl pivoted on the spool frame arranged to engage the ratchet teeth and also to engage the cam surfaces, the inter-relation of said interengaging means, cam-forming recesses and limit means being so arranged that: a. upon retraction of a seat belt which has been withdrawn from the spool, the clutch disc is urged to rotate owing to said frictional engagement with the spool and the brake disc is urged by the spigot to rotate, whereby the pawl recess moves into alignment with the pawl but the cam surface of the clutch disc pivots the pawl out of engagement with the ratchet teeth, b. upon initial further withdrawal of the seat belt from the spool and during said limited relative rotation between said clutch and brake discs the clutch disc is urged to rotate in a reverse direction to place its radially inwardly extending recess into alignment with the pawl, whereby the pawl pivots to engage the teeth of the ratchet, and, c. upon further withdrawal beyond the limit of said limited relative rotation of the discs, the spigot of the clutch disc imparts rotation to the brake disc and the cam surface of the brake disc lifts and pivots the pawl out of engagement with the ratchet teeth.

Claim 10

A take up spool lug according to claim 7 wherein said clutch disc has a clutch friction pad thereon in frictional engagement with said spool; said brake disc has a brake friction pad thereon in frictional engagement with said spool frame, the clutch friction pad being displaced further from the spool axis than the brake friction pad whereby the clutch friction pad transmits more drive torque than the brake friction pad and upon spool rotation the clutch disc causes rotary movement of the brake disc.

Claim 11

A take up spool lug according to claim 7 wherein said spigot is outstanding from a face of the clutch disc and lies within a further radially inwardly extending recess in the brake disc, the ends of which recess constitute with the spigot said co-operable limit means.